Abstract
Graphene is not an ideal anode material of Li-ion batteries because of its low packing density and low initial Coulombic Efficiency although it shows much higher specific capacity than graphite. Herein, we report a sandwich-structured hybrid anode material which integrates the nitrogen-doped amorphous carbon nanoarrays on both sides of graphene nanoplatelets. The former provides high capacity and excellent rate capability, while the latter stabilizes the cycle performance, both of them brought out outstanding electrochemical properties to the hybrid anode. High discharge capacities of 562 and 217 mA h g-1 are obtained at current densities of 0.1 and 3 A g-1, respectively, which are much higher than those of the starting graphene nanoplatelets (404 and 81 mA h g-1, respectively). Moreover, a discharge capacity of 540 mA h g-1 is maintained after 300 cycles at 0.5 A g-1, demonstrating an excellent cycle stability. This study provides a facile process to prop up the 2 D graphene nanoplatelets with vertically aligned carbon nanoarrays, which may push forward the application of graphene as anode material of Li-ion batteries because of the avoided aggregation and additional Li storage capacity contributed by the N-doped amorphous carbon.
Highlights
The rapid development of electric vehicles (EVs) calls for reliable energy storage devices with both high energy and high power densities
The bright-field TEM images shown in Figures 2a,b at different magnifications indicate that the amorphous carbon nanoarrays vertically grew on both sides of the graphene nanoplatelets
A HADDF image (Figure 2c) clearly reveals that the carbon nanoarrays growing on the thin graphene nanoplatelets are highly porous
Summary
The rapid development of electric vehicles (EVs) calls for reliable energy storage devices with both high energy and high power densities. Li-ion batteries (LIBs) are currently the most widely used power sources of EVs, but their low energy density is still one major concern of EV manufacturers and customers, as one always hopes to drive as long as possible at a single charge. The inferior energy and power densities of LIBs are majorly determined by the intrinsic characteristics of their electrode materials (Nitta et al, 2015). Taking the state-of-theart anode material of LIBs, graphite, as an example, it has high reversibility and stable cycle performance, but limited capacity (only 372 mA h g−1 theoretically) and rate performance. This makes graphite not an ideal anode material for high power LIBs (Zhang et al, 2014)
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